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* [gcc r13-6324] libstdc++: Optimize net::ip::address_v4::to_string()
@ 2023-02-24 14:26 Jonathan Wakely
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From: Jonathan Wakely @ 2023-02-24 14:26 UTC (permalink / raw)
To: gcc-cvs, libstdc++-cvs
https://gcc.gnu.org/g:363f0ef50bd143fce77a1c7905b0ed707f4a9358
commit r13-6324-g363f0ef50bd143fce77a1c7905b0ed707f4a9358
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Thu Feb 23 17:39:33 2023 +0000
libstdc++: Optimize net::ip::address_v4::to_string()
This is an order of magnitude faster than calling inet_ntop (and not
only because we now avoid allocating a string that is one byte larger
than the SSO buffer).
libstdc++-v3/ChangeLog:
* include/experimental/internet (address_v4::to_string):
Optimize.
* testsuite/experimental/net/internet/address/v4/members.cc:
Check more addresses.
Diff:
---
libstdc++-v3/include/experimental/internet | 28 +++++++++++++++-------
.../net/internet/address/v4/members.cc | 11 +++++++++
2 files changed, 31 insertions(+), 8 deletions(-)
diff --git a/libstdc++-v3/include/experimental/internet b/libstdc++-v3/include/experimental/internet
index 707370d5611..08bd0db4bb2 100644
--- a/libstdc++-v3/include/experimental/internet
+++ b/libstdc++-v3/include/experimental/internet
@@ -44,6 +44,7 @@
#include <sstream>
#include <cstdint>
#include <experimental/string_view>
+#include <bits/charconv.h>
#ifdef _GLIBCXX_HAVE_UNISTD_H
# include <unistd.h>
#endif
@@ -241,17 +242,28 @@ namespace ip
__string_with<_Allocator>
to_string(const _Allocator& __a = _Allocator()) const
{
-#ifdef _GLIBCXX_HAVE_ARPA_INET_H
+ auto __write = [__addr = to_uint()](char* __p, size_t __n) {
+ auto __to_chars = [](char* __p, uint8_t __v) {
+ unsigned __n = __v >= 100u ? 3 : __v >= 10u ? 2 : 1;
+ std::__detail::__to_chars_10_impl(__p, __n, __v);
+ return __p + __n;
+ };
+ const auto __begin = __p;
+ __p = __to_chars(__p, uint8_t(__addr >> 24));
+ for (int __i = 2; __i >= 0; __i--) {
+ *__p++ = '.';
+ __p = __to_chars(__p, uint8_t(__addr >> (__i * 8)));
+ }
+ return __p - __begin;
+ };
__string_with<_Allocator> __str(__a);
- __str.resize(INET_ADDRSTRLEN);
- if (inet_ntop(AF_INET, &_M_addr, &__str.front(), __str.size()))
- __str.erase(__str.find('\0'));
- else
- __str.resize(0);
- return __str;
+#if __cpp_lib_string_resize_and_overwrite
+ __str.resize_and_overwrite(15, __write);
#else
- std::__throw_system_error((int)__unsupported_err());
+ __str.resize(15);
+ __str.resize(__write(&__str.front(), 15));
#endif
+ return __str;
}
// static members:
diff --git a/libstdc++-v3/testsuite/experimental/net/internet/address/v4/members.cc b/libstdc++-v3/testsuite/experimental/net/internet/address/v4/members.cc
index df19b11804d..c40a8103664 100644
--- a/libstdc++-v3/testsuite/experimental/net/internet/address/v4/members.cc
+++ b/libstdc++-v3/testsuite/experimental/net/internet/address/v4/members.cc
@@ -22,6 +22,7 @@
#include <experimental/internet>
#include <sstream>
#include <testsuite_hooks.h>
+#include <testsuite_allocator.h>
using std::experimental::net::ip::address_v4;
@@ -100,6 +101,16 @@ test04()
VERIFY( address_v4::any().to_string() == "0.0.0.0" );
VERIFY( address_v4::loopback().to_string() == "127.0.0.1" );
VERIFY( address_v4::broadcast().to_string() == "255.255.255.255" );
+ using b = address_v4::bytes_type;
+ VERIFY( address_v4(b(1, 23, 45, 67)).to_string() == "1.23.45.67" );
+ VERIFY( address_v4(b(12, 34, 56, 78)).to_string() == "12.34.56.78" );
+ VERIFY( address_v4(b(123, 4, 5, 6)).to_string() == "123.4.5.6" );
+ VERIFY( address_v4(b(123, 234, 124, 235)).to_string() == "123.234.124.235" );
+
+ __gnu_test::uneq_allocator<char> alloc(123);
+ auto str = address_v4(b(12, 34, 56, 78)).to_string(alloc);
+ VERIFY(str.get_allocator().get_personality() == alloc.get_personality());
+ VERIFY( str == "12.34.56.78" );
}
void
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